NTB: Enable Snoop on Primary Side

Enable Snoop from Primary to Secondary side on BAR23 and BAR45 on all
TLPs.  Previously, Snoop was only enabled from Secondary to Primary
side.  This can have a performance improvement on some workloads.

Also, make the code more obvious about how the link is being enabled.
Signed-off-by: Jon Mason <jon.mason@intel.com>

drivers/ntb/ntb_hw.c

@@ -1316,10 +1316,16 @@ static void ntb_hw_link_up(struct ntb_device *ndev)
 {
 	if (ndev->conn_type == NTB_CONN_TRANSPARENT)
 		ntb_link_event(ndev, NTB_LINK_UP);
-	else
+	else {
+		u32 ntb_cntl;
+
 		/* Let's bring the NTB link up */
-		writel(NTB_CNTL_BAR23_SNOOP | NTB_CNTL_BAR45_SNOOP,
-		       ndev->reg_ofs.lnk_cntl);
+		ntb_cntl = readl(ndev->reg_ofs.lnk_cntl);
+		ntb_cntl &= ~(NTB_CNTL_LINK_DISABLE | NTB_CNTL_CFG_LOCK);
+		ntb_cntl |= NTB_CNTL_P2S_BAR23_SNOOP | NTB_CNTL_S2P_BAR23_SNOOP;
+		ntb_cntl |= NTB_CNTL_P2S_BAR45_SNOOP | NTB_CNTL_S2P_BAR45_SNOOP;
+		writel(ntb_cntl, ndev->reg_ofs.lnk_cntl);
+	}
 }
 
 static void ntb_hw_link_down(struct ntb_device *ndev)
@@ -1333,8 +1339,9 @@ static void ntb_hw_link_down(struct ntb_device *ndev)
 
 	/* Bring NTB link down */
 	ntb_cntl = readl(ndev->reg_ofs.lnk_cntl);
-	ntb_cntl &= ~(NTB_CNTL_BAR23_SNOOP | NTB_CNTL_BAR45_SNOOP);
-	ntb_cntl |= NTB_CNTL_LINK_DISABLE;
+	ntb_cntl &= ~(NTB_CNTL_P2S_BAR23_SNOOP | NTB_CNTL_S2P_BAR23_SNOOP);
+	ntb_cntl &= ~(NTB_CNTL_P2S_BAR45_SNOOP | NTB_CNTL_S2P_BAR45_SNOOP);
+	ntb_cntl |= NTB_CNTL_LINK_DISABLE | NTB_CNTL_CFG_LOCK;
 	writel(ntb_cntl, ndev->reg_ofs.lnk_cntl);
 }
 

drivers/ntb/ntb_regs.h

@@ -143,11 +143,13 @@
 #define BWD_LTSSMSTATEJMP_FORCEDETECT	(1 << 2)
 #define BWD_IBIST_ERR_OFLOW	0x7FFF7FFF
 
-#define NTB_CNTL_CFG_LOCK	(1 << 0)
-#define NTB_CNTL_LINK_DISABLE	(1 << 1)
-#define NTB_CNTL_BAR23_SNOOP	(1 << 2)
-#define NTB_CNTL_BAR45_SNOOP	(1 << 6)
-#define BWD_CNTL_LINK_DOWN	(1 << 16)
+#define NTB_CNTL_CFG_LOCK		(1 << 0)
+#define NTB_CNTL_LINK_DISABLE		(1 << 1)
+#define NTB_CNTL_S2P_BAR23_SNOOP	(1 << 2)
+#define NTB_CNTL_P2S_BAR23_SNOOP	(1 << 4)
+#define NTB_CNTL_S2P_BAR45_SNOOP	(1 << 6)
+#define NTB_CNTL_P2S_BAR45_SNOOP	(1 << 8)
+#define BWD_CNTL_LINK_DOWN		(1 << 16)
 
 #define NTB_PPD_OFFSET		0x00D4
 #define SNB_PPD_CONN_TYPE	0x0003